1. Field of the Invention
This invention relates to the preparation of herpesvirus subunit vaccines, and in particular to Herpes simplex type 1 and 2 vaccines.
Herpesviruses are ubiquitous in nature; natural hosts include the frog, chicken, mouse, guinea pig, cat, dog, swine, cow, horse, monkey and man. Man is the natural host for Herpes simplex type 1 and 2, varicella/zoster, cytomegalovirus and Epstein-Barr virus (EBV) and can be a temporary host for herpes B virus of monkeys with serious consequences. Clinical illness caused by herpes viruses presents a significant health problem for which no effective preventive measures are available. Herpes simplex type 1 and 2 are antigenically related, but generally cause infections at different sites. Herpes simplex type 1 (HSV1) is transmitted by the oral-respiratory route and is most frequently associated with oral lesions. Herpes simplex type 2 (HSV2) is transmitted venereally and is usually responsible for herpes genitalis and neonatal herpes. The role of these virus in chronic disease has not been defined. However, HSV2 has been implicated in genital cancer on the basis of: (a) seroepidemiologic findings, (b) demonstration of herpesvirus antigens or viral nucleic acid in neoplastic tissue, and (c) in vitro transformation of a variety of cells, including human cells, by irradiated virus.
Members of the herpesvirus group are relatively large enveloped ether-sensitive DNA viruses. Herpes simplex type 1 viruses have been shown characteristically to contain two predominant molecular weight groups of envelope glycoproteins whereas type 2 viruses have been shown characteristically to possess three predominant molecular weight groups of envelope glycoproteins. Some of these glycoproteins have been isolated and shown to induce neutralizing antibody in animals.
Herpesviruses present unique and individual problems for vaccine development, especially for use in man. Generally, viral vaccines, whether live attenuated vaccines or killed inactivated vaccines, are prepared from virus contained in animal host fluids or cell culture fluids or viral concentrates derived therefrom. However, herpesviruses in general tend to be more cell-associated than many other viruses, i.e., do not shed into the fluids, and, especially some members of the group, do not propagate readily to the high level of virions required for large scale manufacture of vaccine. Additionally, certain herpesviruses, such as HSV2 and EBV, are suspected of being oncogenic for man. Preparation of vaccines from such viruses presents a special problem in that the vaccine must be free of any viral genetic information capable of inducing cancer. Even inactivated whole virus vaccines are viewed as potentially hazardous in such cases because they contain viral nucleic acid. Recently, efforts toward improved viral vaccines have lead to the development of subunit or "split" vaccines to reduce or remove unwanted host or viral components in the vaccines. An example in point is the preparation of influenza viral subunit vaccine from infected chick egg allantoic fluid to reduce the toxicity and pyrogenicity as described in U.S. Pat. No. 3,962,421. However, such subunit vaccines have not emphasized or demonstrated the removal and/or deactivation of viral genetic information as will be needed for viruses suspected of playing an etiologic role in cancer.
2. Objects of the Invention
It is an object of the present invention to provide a subunit antigen for a herpes virus. Another object is to provide an immunogenic but nonpathogenic herpes subunit antigen. A further object is to provide a herpes subunit antigen which can be used as a vaccine which protects a subject against the effects of this virus on both initial and subsequent challenge. Yet another object is to provide a method for effectively solubilizing and extracting viral-directed glycoproteins from virus-infected cells utilizing a surfactant and salt. Another object is to provide a method for concentrating the glycoproteins and removing unwanted protein and nucleic acid. Another object is to provide compositions containing a herpes subunit which are stable and storable. Still another object is to provide physiologically acceptable compositions for administering a herpes subunit vaccine. These and other objects of the present invention will be apparent from the following description.